Metastability

related topics
{acid, form, water}
{math, energy, light}
{island, water, area}
{area, part, region}
{disease, patient, cell}
{theory, work, human}
{water, park, boat}

Metastability is a general scientific concept which describes states of delicate equilibrium. A system is in a metastable state when it is in equilibrium (not changing with time) but is susceptible to fall into lower-energy states with only slight interaction. It is analogous to being at the bottom of a small valley when there is a deeper valley close by — a local stability of a system at a local (but not global) minimum of a potential.

Almost any system can demonstrate metastability, but it is most prevalent in systems of weakly interacting particles in physics and chemistry. Often, the weak interaction between particles is the only energy barrier that must be overcome for the system to reach a lower-energy state.

Contents

Quantum mechanics

Aggregated systems of subatomic particles — as described by the quantum mechanics (quarks inside the nucleons and nucleons inside the atomic nuclei, electronic systems of atoms inside molecules or atomic clusters) — are found to have many (a set of) distinguishable states of which only one is indefinitely stable: the ground state or global minimum.

All other states besides the 'ground state' have higher, 'excited' energies. Of all these other states, metastable are the ones having lifetimes lasting at least 102-103 times longer than the shortest lived states of the set.

A metastable state is then long lived (locally stable with respect to configurations of 'neighbouring' energies) but not eternal (as the global minimum is). Being 'excited' - of an energy value above the 'ground' - it will have to eventually 'de-excite'. Indeed, above the absolute 0 K temperature, all system's states, metastable or not, have a non-zero probability to eventually 'decay' or spontaneously fall onto the ground state via tunnelling due to internal thermal fluctuations (in 'position' and 'velocity').

Full article ▸

related documents
Triple point
Cis-trans isomerism
Crystal
Alessandro Volta
Hydrophobe
Colloid
Stereoisomerism
Proton pump
Dmitri Mendeleev
Spinel
Electrochemical cell
Cryostasis (clathrate hydrates)
Piperidine
Ammonium
Quaternary structure
Asparagine
Butanol
Peptide nucleic acid
Superoxide dismutase
Ostwald process
Acridine
Haematoxylin
Exon
Primary nutritional groups
Calcium oxide
Acetonitrile
S-block
Methionine
Talc
Borate